1. Field of the Invention
The present invention relates generally to a locking device and, in particular, an electronic locking device.
2. Description of the Related Art
Various electronic locking devices have been suggested for controlling access to large numbers of areas through doors by a large number of individuals. Many of these devices utilize card readers, push-buttons, dials, etc. to activate the locking device.
One such device is disclosed in U.S. Pat. No. 5,038,122 issued to Clark. The device disclosed in Clark opens a lock in response to a correct code entered through a keyboard and/or to a chronological schedule enabled by a clock marking real time. An LED provides a wireless link to a hand-held printer so that the device may be programmed with access codes and time schedules. The printer also prints out a list of users and times of entry.
One problem with the device disclosed in Clark is that the electromechanical drive system is difficult to assemble because of the engagement of the spring through a set screw. The spring also has a compound shape with two different pitch and hook formations at the end of the spring which again makes alignment and assembly of the system very difficult. Another problem with the device disclosed in Clark is that there is a significant amount of friction generated by the rotary and linearly moving components which results in increased electric power consumption and hence reduced battery life.